High Pixels Per Inch (PPI) has been always an importance target in the display field, and once became an important selling point of products such as mobile phones and televisions etc. However, the high PPI also brings some disadvantages while bringing advantages of good viewing effect and so on. The high PPI will result in increase in the data processed by the graphics processing unit (GPU), thereby leading to a large power consumption of the battery.
Actually, a resolution of human eyes is not always changeless. It will change at any time based on the distance, the environment, and the running speed of the image. One of the important theories is exactly the “retina” standard proposed by Apple Inc. When a distance between the viewer and the display screen is 10-12 inches (about 25-30 cm), the viewer's retina will not be able to resolve pixel points, i.e., will not have granular sensation, as long as the resolution of the display screen reaches 300 pixel points per inch (300 ppi).
Therefore, when human eyes are very close to the mobile phone, a high resolution of the mobile phone itself can be used, in order to enable a consumer not to see small flaws of the display screen and try to exhibit perfect images. However, when the screen is relatively far from the user, even if the resolution does not meet the above resolution, the user will not resolve the pixel points either. Hence, it is not necessary to keep the display screen at a relatively high resolution all the time and thus result in too much power consumption.